[bcm283x_pwm] Add documentation for the second PWM channel

Document sysctls for the second PWM channel added in r335855
Also fix some minor style issues and a typo.

Approved by:	re (gjb)
Submitted by:	bobf@mrp3.com
Reviewed by:	0mp
Differential Revision:	https://reviews.freebsd.org/D17084

1 files changed, 29 insertions, 16 deletions

diff --git a/share/man/man4/man4.arm/bcm283x_pwm.4 b/share/man/man4/man4.arm/bcm283x_pwm.4
index 2c232d35f75b..2b1266a7046a 100644
--- a/share/man/man4/man4.arm/bcm283x_pwm.4
+++ b/share/man/man4/man4.arm/bcm283x_pwm.4
@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd January 22, 2017
+.Dd September 10, 2018
 .Dt BCM283X_PWM 4
 .Os
 .Sh NAME
@@ -38,43 +38,56 @@
 .Sh DESCRIPTION
 The
 .Nm
-driver provides access to the PWM engine on GPIO12 of Rpi 2 and 3 hardware.
+driver provides access to the PWM engine on GPIO12 of Raspberry Pi 2 and 3 hardware.
 .Pp
 The PWM hardware is controlled via the
 .Xr sysctl 8
 interface:
 .Bd -literal
 dev.pwm.0.mode: 1
+dev.pwm.0.mode2: 1
 dev.pwm.0.freq: 125000000
 dev.pwm.0.ratio: 2500
+dev.pwm.0.ratio2: 2500
 dev.pwm.0.period: 10000
+dev.pwm.0.period2: 10000
 dev.pwm.0.pwm_freq: 12500
+dev.pwm.0.pwm_freq2: 12500
 .Ed
-.Bl -tag -width ".Va dev.pwm.0.mode"
-.It Va dev.pwm.0.mode
+.Bl -tag -width ".Va dev.pwm"
+.It Va dev.pwm.0.mode , dev.pwm.0.mode2
+PWM Mode for channels 1 and 2.
 Three modes exist, 0=off, 1=PWM, 2=N/M.
 The N/M mode is a first order delta-sigma mode, which makes a quite
 handy DAC output with a trivial RC lowpass filter.
 .Pp
 .It Va dev.pwm.0.freq
 The input frequency to the PWM hardware in Hz.
-Minmum frequency is 123 kHz, maximum frequency is 125 MHz.
-.It Va dev.pwm.0.period
+Applies to both channels 1 and 2.
+Minimum frequency is 123 kHz, maximum frequency is 125 MHz.
+.It Va dev.pwm.0.period , dev.pwm.0.period2
 The period length in cycles.
-In PWM mode, the output frequency will be
+In PWM mode, the output frequencies will be
 (
 .Va dev.pwm.0.freq
 /
-.Va dev.pwm.0.period .
-)
-In N/M mode this is the 'M'
-.It Va dev.pwm.0.ratio
-The "on" period in cycles.
+.Va dev.pwm.period
+) and (
+.Va dev.pwm.0.freq2
+/
+.Va dev.pwm.0.period2
+).
+In N/M mode this is the 'M'.
+.It Va dev.pwm.0.ratio , dev.pwm.0.ratio2
+The "on" period in cycles for PWM channels 1 and 2.
 In PWM mode, to get a 25% dutycycle, set this to 25% of
-.Va dev.pwm.0.period .
-In N/M mode this is the 'N'
-.It Va dev.pwm.0.pwm_freq
-The calculated PWM output frequency in PWM mode.
+.Va dev.pwm.0.period
+or
+.Va dev.pwm.0.period2 ,
+as appropriate.
+In N/M mode this is the 'N'.
+.It Va dev.pwm.0.pwm_freq , dev.pwm.0.pwm_freq2
+The calculated PWM output frequencies in PWM mode, for channels 1 and 2.
 .El
 .Pp
 .Sh NOTES